Self-centering electrical switch



April l5, 1969 j J. A. BRAUN 3,439,138

l SELF-CENTERING' ELECTRICAL SWITCH v med Dec. so, 196e Sheet of 2 J. A. BRAUN SELF-CENTERING ELECTRICAL SWITCH April l5, 1969 Sheet of 2 Filed Dec. 30, 1966 United States Patent O 3,439,138 SELF-CENTERING ELECTRICAL SWITCH .lohn A. Braun, Attleboro, Mass., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Dec. 30, 1966, Ser. No. 606,371 Int. Cl. H01h 21/00, 21/22 U.S. Cl. 200--67 3 Claims ABSTRACT OF THE DISCLOSURE A switch wherein the actuator returns to a center position while maintaining engagement of one of a pair of movable and fixed contacts for performing a memory function of indicating which set of contacts in a momentary switch was last actuated. The movable contacts are carried by a pivoted contact arm for engagement with the fixed contacts. The actuator is provided with a lost-motion mechanism by mounting a contact arm-engaging roller on an axle for rotating and sliding movement in a pair of elongate slots formed in the lower end of the actuator. A pair of springs return the actuator to a center position.

Background of the invention The invention pertains to electrical switches, and particularly to a memory switch for use with one or more momentary contact switches.

It is sometimes necessary to provide an indicator for indicating `which of a plurality of a momentary contact switches was last actuated. It should be understood, of course, that a momentary contact switch maintains a pair of contacts engaged (or disengaged if used with a relay) only as long as its actuator member is held in an on position. W-hen the mem-ber is released, the switch automatically returns to `a contacts-open or off position to interrupt a circuit connected thereto. Accordingly, when a plurality of such momentary contact switches are utilized, it may be necessary to provide an indicator for indicating which one was last actuated. For example, in certain types of spacecraft it is necessary for the pilot to draw fuel from a plurality of tanks for accomplishing certain maneuvers. Since the fuel tanks in a spacecraft are positioned in a symmetrical pattern about its center of gravity, withdrawal of fuel is alternated between the tanks so that the center of gravity is not excessively changed. Accordingly, a momentary contact switch is provided for the fuel flow valve of each fuel tank. In addition, an indicator, such as a light, is provided for each momentary switch for indicating to the pilot which of the fuel tanks was last used. In the past, each indicator required a latching relay and associated circuitry for maintaining an indicating condition from the time one of the momentary switches was activated to the time that another of' the momentary switches was actuated.

Summary of the invention Accordingly, the invention provides a memory switch which may be ganged to a plurality of momentary switches for concomitant operation. The switch actuator, upon release from either of two alternate positions, returns to center to disengage the contacts of the momentary switches while an additional pair of contacts are held engaged for maintaining an indicator in an indicating condition, fullling a memory function and thereby attaining the object of eliminating the need for a latching relay and its associated circuitry.

The present switch includes two sets of contacts and an actuator for engaging either one of the sets of contacts and disengaging the other of the sets of contacts as the actuator is moved from a first to a second position. Means CII 3,439,138 Patented Apr. 15, 1969 ice are provided for returning the actuator to the first position while maintaining engagement of one of the sets of contacts. Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief description of the drawings FIG. l is a plan view of a momentary and memory switch made according to the present invention;

FIG. 2 is a section of the memory switch taken on line 2-2 of FIG. l;

FIG. 3 is a section showing the switch of FIG. 2 in an actuated position; and

FIG. 4 is an enlarged side elevation of a portion of the switch of FIG. 2 in another position.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Descrip-tion 0j the preferred embodiment Referring 4now to the drawings, a switch assembly 1 is comprised of a housing 3 having a threaded center post 5 with a pair of nuts 7 and a washer 9 thereon. The post 5 may be inserted through a hole in a mounting panel and the nuts 7 tightened to mount the switch assembly 1 in a conventional manner. The housing 3 is divided into three sections containing switches A, B and C. Switch A is a lmemory switch and switches B and C are momentary contact switches. Switches B and C may be of the type disclosed in copending application Serial No. 450,752, filed April 26, 1965, issued as Patent 3,322,914; assigned to the assignee of this invention and to which reference may be had for details of construction.

As best illustrated in FIG. 2, the memory switch A includes a cup-shaped lower housing 11 having a cover 13. An inner layer of electrically insulating material 15 is inserted into the housing part 11 for insulating the switch mechanism therefrom. A pair of fixed contacts 17, 19 are mounted in the Ibottom of the housing 11 and to a pair of terminals 21 and 23, respectively. A center terminal 25 is electrically connected through a conductive U-shaped bracket 27 to a contact on switch arm assembly 29, the latter including a contact arm 31 having a pair of movable contacts 33 and 35 at its ends and a cam plate 37. The cam plate 37 is secured to the contact arm 31 by a pivot pin 39 inserted between a pair of web portions 41, 43 formed respectively on the contact arm 31 and cam plate 37. The cam plate 37 is seated on. a pair of buttons 44 formed on the Contact arm 31 to prevent relative motion of the former on the latter. Therefore, the contact arm assembly 29 including the contact arm 31 and cam plate 37 is pivotal about a transverse axis at pin 39 for engaging and disengaging the fixed and movable contacts 17, 33 and 19, 35.

An actuator 45 is provided for engaging the cam plate 37 to pivot the contact arm assembly 29 about axis 39. The actuator 45 comprises a toggle block 47 having a cylindrical recess 49 slidably receiving a plunger 51. The plunger S1 has an inverted U-shaped yoke 53 at its lower end which is biased into engagement with the cam plate 37 by a coil spring 55 disposed in a recess 57. A lostmotion interconnecting mechanism is provided by mounting an axle 59 of a driver or roller 61 in an arcuate Slot 57 formed in each of the legs of the yoke 53, the roller engaging the cam plate 37 for pivoting the assembly 29 and for maintaining electrical contact between the arm 31 and disc 27. The toggle block 47 is connected to a toggle lever 62 through an aperture 64 in a slidable crossplate 63, the lever `62 being pivoted by a pair of ears 67 on a bushing 65, The crossplate 63 extends laterally within the housing 3 into switch sections B and C for actuating the momentary switches upon operation of toggle lever 62. For example, operation of toggle lever 62 to the left in FIG. 2 will actuate the memory switch contacts 19, 35 and the left set of contacts in momentary switches B and C while operation to the right will actuate contacts 17, 33 and the right set of contacts -in switches B and C. A pair of springs 69 engage the plate 63 and housing 11 to bias the actuator 45 to a center vertical position when the lever 62 is released.

Operation is as follows. The switch A may be connected to a pair of indicating circuits (not shown) through the terminals 21, and 23, 25 for indicating which of the sets of contacts in momentary switches B and C was last actuated. In the position of switch A illustrtaed in FIG. 2, the closed contacts 19, complete a circuit connected between terminals 23 and 25 for indicating, for example, that the right set of contacts in momentary switches B and C, as seen in FIGS, l and 2, were last actuated. The contacts 19, 35 are in engagement. The actuator 45 and toggle lever 62 are in a substantially vertical center position. The shaft 59 and the roller 61 are positioned off-center at the right-hand end of slot 57.

To actuate the left set of contacts in mo-mentary switches B and C, the toggle lever 62 is thrown to the right, as shown in FIG. 3, to pivot the actuator to the left. This causes the roller 61 to roll to the left along the surface of the cam plate 37 with yoke 53 until the roller 61 on the contact arm 29 overtravels center 39 and disen gages the contacts 19, 35 and engages the contacts 17, 33. In this position, the indicator circuit connected between terminals 21 and 25 is actuated and the left set of contacts of the switches B and C are engaged through operation of crossplate 63. In the position of the parts shown in FIG. 3 the toggle lever 62 is -held towards the 4right to maintain engagement of the left set of contacts of the switches B and C. It Should be noted that the block 47 moves in crossplate 63 until it engages the left side of it to move it against the bias of spring 69 and actuate switches B and C.

Upon release of the toggle lever 62 from the FIG. 3 position, the springs 69 cause the actuator 45 to pivot to a center position and disengage the contacts of switches B and C through action of the crossplate 63. However, the roller 61 .remains stationary as the yoke 53 pivots toward the center about axle 59. The lever 62 therefore pivots to the center position illustrated in FIG. 4 leaving the roller 61 at the left end of slot 57 to maintain engagement of contacts 17 and 33 for maintaining an indicator associated with the left set of contacts of switches B and C on to indicate that this set of contacts was last actuated. The operation may of course be repeated reversely to again actuate the opposite set of contacts n switches B and C and switch contacts 19 and 35 by operating the lever 62 to the left.

Thus, a combination switch is provided having a single toggle lever for actuating the contacts of a pair of momentary switches and a memory switch, the latter operating an indicator for indicating which of the momentary switches was last actuated.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What `is claimed is:

1. A self-centering electrical switch comprising a support, a pair of contacts thereon, a pivoted switch arm, said switch arm' having a pivot and carrying a pair of movable contacts for alternate pivotal movement into and out of engagement with said lixed contacts, actuator means for pivoting said switch arm, said actuator means comprising a pivoted lever, spring biased plunger means on said lever, said plunger means having a slot, a driver having lost-motion in said slot and engaging the switch arm for movement thereon on each side of the pivot, and means forming a part of the actuator for returning said lever and plunger to a center position while the driver remains oli-center in said slot for maintaining engagement between one of said iixed and one of said movable contacts.

2. A self-centering electrical switch as set forth in claim 1 further comprising at least one momentary switch having two sets of contacts, said actuator means causing engagement of one set of momentary switch contacts and one of 4said movable and xed contacts when operated in one direction, and the other set of momentary switch contacts and the other movable and iixed contacts when operated in the other direction, said momentary switch contacts disengaging upon return of said lever and plunger to said center position while one of Said fixed and movable contacts remains engaged.

3. A self-centering switch comprising a housing having a pair of fixed contacts therein, a contact arm pivotally mounted on a shaft near its center, said arm carrying a pair of movable contacts for pivotal movement into and out of engagement with said fixed contacts, actuator means for pivoting said contact arm' on said shaft, said actuator means comprising a pivotally mounted toggle lever, a toggle block secured to said toggle lever, a spring biased plunger mounted on said toggle block, and a roller mounted on said plunger for engagement with said contact arm, said roller being rotatable on an axle supported in a pair of arcuate -slots formed in said plunger, said axle being slidable in said slots, and spring means engaging said housing and said toggle block for returning said lever, block and plunger to a center, substantially vertical, position While permitting said roller to `remain oit-center in said slot for maintaining engagement of one of said fixed and movable contacts.

References Cited UNITED STATES PATENTS 2,648,728 8/ 1953 Bollhoefer 2.00-167 2,870,299 l/l959 Cox ZOO-167 3,171,929 3/1965 Jenks et al. 3,294,932 12/1966 Barlow.

ROBERT K. SCHAEFER, Primary Examiner.

DAVID SMITH, J R., Assistant Examiner.

U.S. Cl. X.R. 1200-68 

